Electronic alertness control



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April 4, 1967 Filed- Dec. 30, 1964 Aw xum United States Patent Oil-ice 3,312,508 Patented Apr. 4, 1967 3,312,508 ELECTRONIC ALERTNESS CONTROL William M. Keller, 8864 E. Prairie Road, Skokie, Ill. 60077, and Robert F. Breese, 1609 W. Sherwin Ave., Chicago, Ill. 60626 Filed Dec. 30, 1964, Ser. No. 422,331 16 Claims. (Cl. 303-19) This invention relates to an electronically controlled timing device that is utilized as a prompter to require certain responses from a human operator engaged in controlling machines or processes which require that the operator be alert at all times to insure his own safety and the safety of others. incapacitated through sickness or death or is otherwise inattentive, then the device will operate after a predetermined time period to first sound alarms to alert the operator and then, if the operator still fails to respond, to shut down or stop the machinery or processes being supervised by the operator.

While the timing device described herein is used in the cab of a railroad locomotive and is designed to stop the locomotive and train in the event the locomotive engineer is incapacitated or not alert, it should be apparent that my timing device can also be used in conjunction with the operation of other types of vehicles and machines. The device can also be used in conjunction with processes and operations which require that the operator be alert to perform certain duties.

While it can be expected that the engineer in charge of a railroad locomotive will be alert to his responsibilities, it is also true that any human operator can become drowsy or fall asleep even though he conscientiously tries to prevent this from happening. Furthermore, the human operator can, of course, be stricken unconscious or dead, and such an event can occur quickly with no warning. Thus, there are many contingencies which can arise during the time that the locomotive engineer is in charge of the locomotive and train, and means must be provided to aid the engineer and to initiate safety measures when the engineer is not responding to his duties in a normal manner.

The need for safety means to aid the railroad locomotive engineer or to back-up the engineer in case he becomes incapacitated has long been recognized in the railroad industry and various means have been designed over the years for this purpose. For example, railroad locomotives have in the past been equipped with brake apparatus comprising a dead man or safety control valve device which is operative to initiate the application of the vehicle brakes unless the engineer maintains pressure on a pedal or hand grip. Unfortunately, these safety control features will be nullified if the engineer should become ill or stricken in such a way so as to maintain the pedal or hand grip depressed, or if someone should tamper with the apparatus to retain it in operative position.

Means have also been provided to initiate emergency brake applications on vehicles in the event that the operator is not making the customary movements normally associated with the operation of the vehicle. Other means have been provided which initiate the emergency brake application on the vehicle unless the operator resets certain timing apparatus at periodic intervals. While both types of means have been helpful to some degree, they have not been entirely satisfactory for use in a railroad locomotive becausethey have tended to distract the attention of the locomotive engineer from his normal duties and, in addition, have restricted his movements within the cab of the locomotive.

As the operation of modern railroad trains has required higher speeds, it has become apparent that a safety de- In the event the operator becomes vice which will be of aid to the locomotive engineer must be so designed that its operation will be certain, but at the same time such device must not unduly distract the attention of the engineer nor restrict his normal movements. Furthermore, a safety device of this type must be provided which will defy attempts to tamper with the device to circumvent the operation of the device and render a valuable safety aid useless.

Therefore, it is a primary object of my invention to provide a timing device which can be used in conjunction with the operation of a railroad locomotive to provide a series of preliminary signals to the railroad locomotive engineer and which will act to stop the locomotive by a service brake application in the event that the engineer does not acknowledge the preliminary signals.

It is a further object of my invention to provide such a timing device wherein the preliminary signals will include both visual and audible signals to the engineer.

It is another object of my invention to provide a timing device providing visual signals for a railroad locomotive engineer which will be readily observable but which will not unduly distract the attention of the engineer from his normal duties in the locomotive cab.

`It is a still further object of my invention to provide means asociated with a timing device in a locomotive cab and which canrbe readily adjusted to vary the period of time during which preliminary signals are given to the locomotive engineer before any brake application is initiated by the device.

It is a further object of my invention to provide reset means operable by the locomotive engineer at any time during the series of preliminary signals so that the timing device is reset on a new cycle of preliminary signals and a brake application of the locomotive is prevented.

It is yet another object of my invention to provide a timing device which will be an aid to a railroad locomotive operator and which will operate even though certain components of the device are malfunctioning or are removed frorn the device.

The timing device includes an indicator lamp panel which can be mounted in the cab of a railroad locomotive where it is conveniently visible to the engineer. On this panel there are two concentrically disposed circles of individual electrical lamps and the individual lamps in each circle are sequentially turned on and off by suitable electronic circuits of the device. designed that the sequential advance of the respectively illuminated lamps in the outer circle will be at a faster rate than that of the inner circle. It can be appreciated that if there are the same number of lamps in the two circles of lamps, the outer circle of illuminated lamps will catch up with the inner circle of illuminated lamps at some instant of -time after the cycle has been started. The rate at which the outer circle of lamps will catch up with the inner circle of lamps can be varied by suitable means in the electronic circuits. As an example, in a model of the device the adjustment is such that the outer circle of illuminated lamps advances at a rate twice that of the inner circle of illuminated lamps, and the outer circle of illuminated lamps catches up with the inner circle of illuminated lamps every two minutes. When this occurs, suitable audible warning means such as a buzzer can be made to operate so as to warn the engineer that a certain period of time has elapsed since the commencement of the visual moving lamp display.

If for any reason the engineer is incapable of acknowledging the warning buzzer and resetting the lamp display for another cycle of operation, other electronic circuitry of the device will continue to operate. After a predetermined time period the circuitry will initiate other Vaudible signal means such as a bell and cause the air The circuits are so asiat-ice brake solenoid valve of the locomotive to operate to make a'service application of the train brakes. At any time up to the point where the bell sounds and the brake application is made, the engineer can reset the sequential lamp display and the advancing lamp cycle is repeated.

Thus, in the normal course of events, and assuming the engineer is alert or not incapacitated, the sequential or advancing lamp display will be reset periodically within the time limits of the device by the manual operation ofthe engineer and no service brake application will be initiated by the device. If, however, for some reason the engineer is not alert or is incapacitated, then the sequence of events described above will occur and the locomotive and train will be stopped'. In this event additional circuit means are provided in the device whereby the engin'eer can release the brakes and restart the timing device.

The complete operation of the timing device will be clear Afrom' the detailed description to follow, and in conjunction with the drawings wherein:

FIG. 1 is a block diagram showing the schematic arrangement of the indicator lamp panel and associated circuits, valves, and reset devices. FIG. 2 shows a schematic diagram of circuits of the device which provide the power supply, the pulse circuits, and other circuits used to operate the timing device.

FIG. 3 is a schematic diagram of the electronic circuits designed to sequentially illuminate the lamps in the inner and outer circles of lamps on the indicator lam-p panel. v

` FIG. 4 is a schematic diagram showing external speedcontrol circuitry which can be used in conjunction with the timing device.

FIG. 5 is -a schematic diagram showing one form of the converter used in the external speed-control circuitry.

FIG. 6 is a schematic diagram which shows another form of converter for use in the external speed-control circuitry.

FIG. 7 is a schematic diagram which shows another arrangement for sequentially illuminating the lamps in the inner `and outer circles of lamps on the indicator lamp panel.

FIG. 1 shows a schematic block diagram of one form of the timing device. The direct current power source to operate the device is shown as a locomotive battery 11B,

but it should be understood that the low voltage control Y system which is available on the locomotive can also be used to supply the power for the device. The power source will be approximately 60 to 80 volts direct current. Lead 11 connects the locomotive battery 10 to certain components of the circuit and to a semi-regulated D.C. power supply 12. This power supply 12 is designed to furnish 28 volts D.C. to other components of the device, and the power leads to these components have all been numbered 13 for convenience.

On an indicator lamp panelQgenerally indicated at 14, there are two concentric circles or series of individual electric lamps, the inner circle of which is gener-ally designated at 15 and the outer circle of which is generally designated at 16. Each circle includes twelve individual lamps 17 and 18, respectively, and the inner circle of lamlps 15 is operatively connected to ring counter 19 through lead 20, while the outer circle of lamps 16 is operatively connected to ring counter 21 through lead 22. j The ring counters 19 and 21 .are operatively connected together and to the reset circuits 23 through lead 24.

Ring counter 19 is connected to inner lamp pulse circuits 25 through lead 26 and ring counter 21 is operatively connected to the outer lamp pulse circuits 27 through lead 28. Inner lamp pulse circuits 25, outer lamp pulse circuits 27 and pulse synchronizing circuits 29 are connected together through lead 30. This lead 30 is also connected to the pressure switch 31 and to the warning period timing and pulse circuits 32. The reset circuits l23 are connected through lead 33 to reset initiation devices 34 and through lead 35 to a safety reset device 36. Reset initiation devices 34 and the safety reset device 36 are operatively connected by lead 37.

Lead 38 operatively connects the reset circuits 23 to the warning circuits 39, action circuits 40, and the brake solenoid valve circuits 41. The warning circuits 39 =are connected through lead 42 to an indicator lamp 43 on indicator lamp panel 14. The action circuits are connected through lead 44 to an indicator lamp 45 likewise located on indicator lamp panel 14. The brake solenoid valve circuits 41 are connected through lead 46 to an indicator lamp 47 also located on the indicator lamp panel 14.

A warning buzzer 48 is connected to the warning circuits 39 through lead 49. Action bell 50 is connected through lead 51 to action circuits 40, and a brake solenoid valve 52 is connected through lead 53 to the brake solenoid valve circuits 41. The brake solenoid valve 52 is connected through piping 54 to the air brake system of the locomotive which is not illustrated. Likewise, the pressure switch 31 is connected through piping 55 to the air brake system of the locomotive.

Assuming that the railroad locomotive is stopped with the brakes applied and the engineer is preparing to move the locomotive, the engineer will then apply electric power from the locomotive battery 10 or other suitable power source on the locomotive to the timing device by operating an electrical switch in the lead 11 shown on FIG. 1. This switch is not shown in-FIG. l but will be described in connection with the description of FIG. 2 where this switch is shown at 61. After this has *been done, the engineer can start the operation of the timing device by operating the safety reset device 36 which is a manually operated electrical switch. If the safety reset device is momentarily operated by the engineer, the reset circuits 23 are ene-rgized to close the brake solenoid valve 52 through brake solenoid valve circuits 41 and the brakes on the locomotive can then be released by the engineer. At the same time, the indicator lamp 47 on the indicator lamlp panel 14 is energized to indicate that the brake solenoid valve 52 has been closed.

When the reset circuits 23 -a-re energized, the ring counters 19 and 21 are also energized and the inner lamp pulse circuits 25 and outer lamp pulse circuits 27 operate to deliver electrical pulses to the respective ring counters and to initiate the sequential energization of the individual lamps 17 and 18 in the inner and outer lamp circles 15 and 16.

The timing cycle during which the individual lamps in the outer lamp circle and the inner lamp circle are pro-f gressively energized is under the control of the respective ring counters 21 and 19 and continues until such a time that the lamps at the twelve oclock position in both the inner and outer lamp circles 15 and 16 are simultaneously energized. This time interval can be adjusted to suit various needs and, as will be explained later, the adjustment can be made dependent upon the speed at which the locomotive is traveling At any time during the timing cycle prior to the time when the respective lamps in the inner and outer lamp circles have advanced to the point where they are simultaneously energized at the twelve oclock position, the engineer can reset the ring counters and associated pulse circuits through the reset initiation `devices 34, and the timing cycle is reinitiated. The reset initiation devices 34 are electrical switches operable manually by a foot pedal, or other means.

However, assume that the engineer is incapacitated or inattentive for some reason, and the timing cycle has progressed to the point where the lamps 17 and 18 at the twelve oclock position in both the inner and outer lamp circles 15 and 16 are energized before the engineer resets the lamp circuits. Then at this point or time the warning circuits 39 operate to energize the warning buzzer 48 and the indicator lamp 43. During the warning period, which follows the operation of buzzer 48 and indicator lamp 43 and which involves a predetermined time period of a few seconds, the engineer can still reset the timing device to start a new timing cycle by using the reset initiation devices 34. If he does so, the sequential energization of the electric lamps in the inner and outer lamp circles 15 and 16 is re-initiated and the warning circuits 39 operate to turn off the warning buzzer 48 and to de-energize the indicator lamp 43.

However, assuming that the engineer still does not heed the warning buzzer 4S and indicator lamp 43, then at the end of the predetermined warning period the action circuits 40 will operate to energize the action bell 50. At the same time, the action circuits will energize the indicator lamp 45 and operate in conjunction with the brake solenoid valve circuits 41 to de-energize the brake solenoid valve 52. When the brake solenoid valve 52 is de-energized, the air brake system on the locomotive is vented and there will be a service application of the brakes on the locomotive. After the brakes have been applied, it will be necessary for the locomotive engineer to use the safety reset device 36 before he can release the brakes and start a new timing cycle of the timing device in the manner previously discussed.

FIGS. 2 and 3 of the drawing show the circuits which are indicated by the blocks on FIG. 1 of the drawings, and reference is now made to these figures for a more detailed description of these circuits and the operation thereof. In order to facilitate an understanding of the circuits involved in the timing device, the reference numbers used in FIG. 1 will also be used to designate the corresponding circuits shown in FIGS. 2 and 3. Also, it is believed that it will be helpful if the circuits to be discussed are set forth under appropriate headings which correspond to the designation used on the schematic block diagram of FIG. l.

S emi-reglzzted D.C. power supply Referring to FIG. 2, the semi-regulated direct current power supply is generally indicated at 12 to correspond to the reference numeral used in FIG. 1 of the drawing. The lead from the positive terminal 56 of the power supply is indicated at 57, and fuse 58 is connected in lead 57 before the terminal connection point ,59. Referring to the lower left-hand corner of FIG. 2. It can be seen that the negative side of the system includes fuse 60 and electrical switch 61 connected in series to the negative terminal 62 of the power supply. Diode 63 is connected between fuses 58 and 60 to prevent damage to the components of the timing device in case of reversed power input leads.

The semi-regulated power supply 12 includes Zener diodes 64, 65 and 66. The cathode of Zener diode 64 is connected to the variable power resistor 67 and to the variable power resistor 68 which in turn is connected to the cathode of the Zener diode 65. The resistor 69 is connected between the common terminal point 59 and the cathode of the Zener diode 66. The anodes of each of the three Zener diodes are connected to the negative terminal of the power supply.

The power resistor 67 and Zener diode 64 constitute the main regulator section with the cathode voltage of the Zener diode 64 being around 36 volts D C. The second portion of the regulator section consists of the power resistor 68 and the Zener diode 65 with the cathode voltage of the Zener diode 65 `chosen to be approximately 28 volts D.C. A terminal indicated at 70 is connected to the cathode of Zener diode 65 and is the positive terminal for a 28 Volt supply to furnish power for the ring counter circuits 19 and 21, to be described in detail later.

The portion of the regulator section which includes the power resistor 69 and the Zener diode 66 is designed so that the cathode voltage of the Zener diode is approximately 28 volts D.C. This voltage is furnished to the 6 pulse circuits 25, 27 and 32 through lead 71, and these circuits will be described later.

Two separate 28 volt D.C. sources have been provided in the semi-regulated D.C. power supply 12 so as to prevent the periodic negative voltage transients which occur at the cathode o-f Zener diode 65, due to the operation of the ring counters 19 and 21, from causing any malfunctions in the pulse circuits 25, 27 and 32 shown in the upper right-hand portion of FIG 2.

Lamp 72 and resistor 73 are connected across Zener diode 65 so that the lamp can be operated from the 28 volt cathode voltage of zener diode 65 and will indicate when t-he semi-regulated D.C. power supply is on. This lamp 72 can be mounted on the indicator lamp panel 14 or at some other suitable location in the locomotive cab.

Outer lamp pulse circuits The outer lamp pulse cir-cuits 27 are shown on FIG. 2 immediately to the right of the semi-regulated D.C. power supply 12. These circuits include a potentiometer 74, resistor '75 and capacitor 76 connected in series between the lead 71 and lead 77 connected to the positive and negative terminals, respectively, of the D.C. power supply. Leads 78 and 79 are connected to opposite sides of the potentiometer 74 and there is a potentiometer 80 in lead 79. Terminals 81 and 82 on leads 78 and 79, respectively, are provided for external speed control circuitry which will be described later.

The emitter of an unijunction transistor, generally indi-- cated at 83, is connected between resistor 75 and capacitor 76. Base one of this unijunction transistor 83 is connected to the prima-ry winding of a transformer generally indicated at 84. The other side of the primary winding of this transformer `84 is connected to the negative terminal of the power supply through the common lead 77. The two secondary windings of transformer `84 are labelled 8481 and 8482. The secondary winding 8481 is shown inthe lower left-hand corner of FIG. 2, .and secondary winding 8482 is vshown on FIG. 3. -The connections frorn the secondary windings of transformer 84 to the other circuit-s of the timing device will be described later.

The anode of diode 85 is also connected lbetween resistor 75 and capacitor 76, and the cathode of diode 85 is connected to one side of resisor 86 and to the emitter of transistor 87. The other side of resistor 86 is connected to the positive terminal of the power supply through lead 71. The collector of transistor 87 is connected to lead 77 ,and to the negative terminal of the power supply. The base of the transistor 87 is connected to one side 4of the resistor 88, and the other side of resistor 88 is connected to the anodes of diodes 89 and 90. The cathode of diode 89 is connected to Alead 91, and lead 91 is connected to a contact 92 in the pressure switch generally indicated at 31. The other contact 93 of switch 31 is connected to the negative terminal of the power supply. The function and operation of this Ipressure switch 31 in conjunction with the circuits now 'being described will be further described latter. The cathode of diode is connected to lead 94, and lead 94 extends to a terminal 95. The connections to the other circuits extending from this terminal 95 will `also be described later.

The operation of the outer lamp pulse circuits generally indicated at 27 on FIG. 1, and shown in detail on FIG. 2 of the drawings, can now be described. When the timing device is turned on, and assuming that no external speed control circuitry is associated with the timing device, the capacitor 76 charges up through a total equivalent timing resistance which is equal to the series resistance sum of the potentiometer 74 and the resistor 75. However, if external speed control circuitry, to'be described later, is connected across terminals 81 and y812, a variable electrical resistance is added in parallel with potentiometer 74. This, of course, will be effective to vary the equivalent timing resistance and the charging rate of capacitor 76. As the lpotential on the posit-ive plate of the capacitor 76 reaches the peak point voltage of the emitter of the unijunction transistor 83, this transistor will turn on and discharge the capacitor 76 through 4the primary winding of the transformer 84. This produces sharp rise-time voltage pulses in the secondary windings of the transformer 84 which are then used to operate other `portions of the timing device to tbe described later.

'Ilhe resistance in the base two circuit of the unijunction transistor `83 consists of the series resistors 96 and 97 that are connected to lead 71 with a total value sufcient to provide temperature compensation of the unijunction transistor 83 at the operating voltage of 28 volts. The potentiometer 7'4 can be adjusted to produce output pulses from this circuitry at any desired interval and, as an example, was set to provide output pulses at exactly ve-second intervals in models of the timing device which have been tested.

The pulse sequence of these outer lamp pulse circuits 27 can be interrupted by the operation of :the transistor 87. If the cathodes of diodes 89 and 90 are grounded either individually or simultaneously, the diodes or diode will |become forward biased into conduction, thus allowing base current t-o flow from the -base of Ithe transistor 87 through the limiting resistor 8-8 [to ground so that transistor 87 will be turned on. When Itransistor 87 starts to conduct, the collector current is limited by resistor 86 and the potential at the emitter of the transistor 87 drops from a positive voltage of 28 volts toward a much lower potential, slightly above ground. vSince the cathode of the diode l8.5 is connected to this emitter, the diode 8'5 is now forward biased, and therefore, conducts, thus clamping the positive plate of the capacitor 76 to the same potential or close to ground potential. Under these conditions thel positive plate of the capacitor 76 can never charge lup through'resistors 74 and 7-5 to the `peak point 'voltage `of the unijunction transistor 83, and thus this transistor is unable to periodically turn on and produce output pulses. When the cathodes of diodes 89 and 90 are disconnected from ground, the transistor 87 turns oi and the normal sequential pulse generations of the unijunction v-transistor 83 and associated circuitry resumes operation as above described.

Inner lamp pulse' circuits The inner lamp pulse circuits are shown immediately adjacent and to the right of the outer lamp pulse circuits Z7 just described. One side of a resistor 98 is connected to lead 71 and the other side of this resistor is connected to the emitter of a transistor 99, and to the cathode of a diode 100. The collector of transistor 919 is connected to lead 77 and the base of the transistor 99 isfconnected to one side of resistor 101. The other side of the resistor 101 is connected to the anodes of diodes 102, 103 and 104. The diode .104 forms part of other circuits which will be described more in detail later.

The cathode of diode 102 is connected through lead 94 to the terminal point 95, ywhile the cathode of diode 103 is connected to the lead 91 going to the pressure switch 31. The anode of diode 100' is connected lbetween one side of resistor 105 .and one side of capacitor l106. The other side of resistor 105 is connected to lead 71 and the other side of capacitor 106 is connected to lead 77. A potentiometer 107 is connected across the capacitor 106.

The emitter of an unijunction transistor 108 is also connected between resistor 105 and capacitor 106. Base two of unijunction transistor :108 ris connected to one side of resistor 109 and the ibase one is lconnected to the primary winding of a transformer generally indicated at 1l10. The other side of resistor 109 is connected to one side ofthe resistor 97. The other side of the primary winding of transformer 110 is connected to lead 77 and to the negative terminal of the power supply. The secondary winding of transformer 1110 lis designated as 1,105. -This secondary winding 1108 is also shown on 8 FIG. 3, and the connections from this secondary winding 1108 to the ring counter `19 will be described later.

The operation of the inner lamp pulse circuitry is similar to that of the outer lamp pulse circuits. Capacitor 106 charges up through resistor until it reaches a maximum potential ydetermined by the voitage divider action of the series resistances 105 and 107. The value of the potentiometer 107 is set in advance such that the maximum potential that can be reached by the top plate of the capacitor 106 is slightly less, approximately 1 or 2 volts, than the actual peak point potential of the emitter of the unijunction transistor 108 in the absence of any synchroni- Zation pulse occuring across the resistance 97 due to the operation of the unijunction transistor 03 and its associated circuitry.

The base two resistance of the unijunction transistor 108 consists of the series resistors 97 and 109 with a total value suiiicient to provide temperature compensation of the transistor 108 at the operating voltage of 28 volts.

It should be noted that the resistor 97 is common to the base two circuits of both unijunction transistor 83 and unijunction transistor 108 and the circuit is used to provide a highly accurate synchronization of the output pulses from both of these transistors. Thus, if there is a charge on the capacitor 106 such that the potential of the top plate of this .capacitor is just slightly less than the firing potential of the unijunction transistor 108 and the unijunction transistor 83 lires, then transistor 108 will also fire in synchronization with the transistor 83. When the unijunction transistor 108 turns on, the capacitor 106 discha-rges through the primary Winding of the ltransformer producing a sharp rise-time voltage pulse in the secondary winding 1108 of transformer 110 which is used to operate other portions of the circuitry in a manner to be discussed later.

The pulse sequence of these circuits can be interrupted by the operation of the transistor 99 through its associated circuitry and occurs if the cathodes of the diodes 102, 103 and 104 are grounded either singularly or simultaneously to cause them to conduct and turn on the transistor 99. The collector current of this transistor 99 is limited by the resistor 98 and as the potential at the emitter of the transistor 99 falls toward -a potential slightly above ground, diode 100 clamps the positive plate of the capacitor 106 to the same potential, thus stopping the periodic pulse generation operations of unijunction transistor 108. If the cathodes of the diodes 102., 103 and 104 are ungrounded, then the transistor 99 is turned off and the unijunction transistor 108 and associated circuitry is returned to normal operation.

Pulse synchronizing circuits The lamps 18 in the outer lamp circle 16 are energized by the appropriate pulse circuits at a rate twice that of the lamps 17 in the inner `lamp circle 15. In order to insure this ratio of pulse delivery, it is necessary to synchronize the outer lamp pulse circuits and the inner lamp pulse circuits, and the circuitry involved for this purpose is shown at the lower right-hand section of FIG. 2.

The positive terminal 70 of the direct current power supply is connected to resistors 111 and 112. Resistor 111 is connected to the anode of silicon controlled rectier 113. The cathode of diode 104 is connected between esistor 111 and the anode of the silicon controlled rectier 113 and to one plate of capacitor 114. The other plate of the capacitor 114 is connected to ground. The

connection between the cathode of diode 104 and capacitor 114 also extends to one side of resistor 115. The other side of resistor 115 is connected to the cathode of diode 116 and to one plate of capacit-or 117. The other plate of capacitor 117 is connected to the gate of silicon controlled rectifier 11S and to a resistor 119. One side of resistor 112 is connected to the anode of silicon controlled rectifier 118. The other side of resistor 119 is connected to the cathode of silicon controlled rectifier 113 and to a 9 common connection of resistor 120 and the cathode of the silicon controlled rectifier 113. The other side of resistor 120 is connected to a terminal point 121. The gate of silicon controlled rectifier 113 and one side of capacitor 122 are also connected to this terminal 121.

The cathodes of silicon controlled rectiers 113 and 118 are connected through lead 123 to one terminal of an air core inductor 124. The other plate of capacitor 122 is connected to a common connection between one side of resistor 125 and the cathode of a diode 126. The other side of resistor 125 is connected to one plate of capacitor 127 and to the common connection between the resistor 112 and the anode of silicon controlled rectifier 118. The other plate of capacitor 127 is connected to ground.

The -anodes of diodes 116 and 126 are connected together and to a terminal point 128. This terminal point 128 is also shown near the center portion of FIG. 3, and is connected to a lead 129 which connects the anodes of the diodes of all stages of the outer ring counter circuit. One side of resistor 130 is connected to. this lead 129 and the other side of the resistor 130 is connected to ground and to one side of lan air core inductor 131.

The circuits involved to synchronize the outer lamp and inner lamp pulse circuits -operate in the followingV manner. Referring again to FIG. 2, when power is first applied to. the timing device, -both silicon controlled rectifier 113 and silicon controlled rectifier 118 remain blocking. The activation of the safety reset device 36 to start the oper-ation of the timing device turns on the silicon controlled rectifier 113 by means of circuitry described below. When the silicon controlled rectifier 113 turns on, it clamps the lower end of resistor 101 to a potential slightly above ground because of the clamping action of diode 104. This activates the transistor 99 and associated circuitry so that the potential of the top plate of the capacitor 106 is clamped at a sufficiently low potential to prevent the firing of the unijunction transistor 108.

At the end of the first pulse `cycle for the outer lamp circuits, the unijunction transistor 83 fires and a pulse is delivered through the secondary winding 84S2 of transformer 84 associated with the ring counter 21, through capacitor 132 to the lead 129 and to the terminal 128, as shown in FIG. 3. As shown on FIG. 2, terminal 128 is common to the anodes of both diodes 116 and 126 so that this pulse passes through diode 116 and capacitor 117 to the gate of silicon controlled rectifier 118, and this rectifier -is turned on. The sudden increase in current fiow through the inductor 124 together with the action of the capacitor 114 turns off the silicon controlled rectifier 113. When silicon controlled rectifier 113 is turned off, the anode of diode 104 rises to a value of approximately 28 volts and transistor 99 and associated circuitry is turne-d off. This allows the capacitor 106 to start charging to more positive values which will be sufiicient to fire the unijunction transistor 108 at some later time.

When the unijunction transistor 83 fires again, the unijunction transistor 108 will now fire because of the proper charge on the capacitor 106. The pulse through transformer 84 will also be transmitted through lead 129 and terminal 128 to the anodes of the diodes 116 and 126. This pulse will pass through the diode 126 and the capacitor 122 to the gate of the silicon controlled rectifier 113 to turn on this rectifier. The sudden increase in current iiow through the air core inductor 124, together with the action of the capacitor 127, turns off the silicon controlled rectifier 118. When the silicon controlled rectifier 113 turns on, it again starts the operation of transistor 99 and associated circuitry so that the unijunction transistor 108 is prevented from firing as previously described.

From the above description it can be seen that the circuit arrangement is designed to make the unijunction transistor 108 and associated circuitry inoperative during every other pulsing of the transformer 84 through the action of the unijunction transistor 83. This produces a pulse rate synchronization which is constant virregardless of the setting of the potentiometer 74 and the timing period of the pulse circuitry can be varied uniformly by means of external speed control circuitry which will be discussed later.

The operation of the safety reset device generally indicated at 36 on FIGS. 1 and 2, and the operation of the reset initiation devices generally indicated at 34 on FIGS. 1 and 2 of the drawings, will also cause the activation of the silicon controlled rectifier 113. As disclosed on FIG. 2, contacts 133, 134, 135 and 136 of the safety reset device 36 and reset initiation devices 34, respectively, are connected to the positive terminal of the direct current supply for thetiming device by means of lead 137. Contact 138 of the safety reset device is connected to the anode of diode 139 while the corresponding contacts 140, 142 and 142 of the reset initiation devices are connected to the cathode of the diode 139 and to one plate of capacitor 143. The other plate of the capacitor is connected to one side of resistor 144. The other side of the resistor 144 is connected to the anode of a diode 145 and the cathode of this diode is connected to one side of the primary winding of transformer 146. The other side of the primary winding of the transformer 146 is connected to the negative or ground terminal of the power source for the device through a lead 147.

Transformer 146 has two secondary windings, one of which 14651 is shown on FIG. 2 associated with the silicon controlled rectier 113 and the other of which 14682 is shown on FIG. 3 at the right central portion thereof. Referring specifically to FIG. 2, it can be seen that one side of the secondary winding 14681 of transformer 146 is grounded while the other side is connected to the anode of diode 148. The cathode of this diode is connected to resistor 149 and the other side of resistor 149 is connected to one side of resistor 150 and to one plate of capacitor 151. The other side of resistor 150 is grounded and the other plate of the capacitor 151 is connected to the terminal point 121.

With the above described arrangement, the operation of the safety reset device 36 or any of the reset initiation devices 34 cause the activation of silicon controlled rectifier 113 in the following manner. A positive ypulse ap'- pearing in the primary winding of the transformer 146, due to the closing of any of the switches in the safety reset device 36 or reset initiation devices 34, results in a positive pulse appearing in each of the two secondary windings of transformer 146. In the case of the circuitry shown on FIG. 2, this pulse passes from secondary winding 14681 through the diode 148, resistor 159, capacitor 151 and to the gate of silicon controlled rectifier 113. If the silicon controlled rectifier 113 `happens to be on at this instant, it remains turned on. However, if the silicon controlled rectifier 113 is off at this instant, it is turned on, thus turning off the silicon controlled rectifier 118 1n the manner described above. Thus the proper sequence of lamp circle timing pulses is synchronized in an exact 2:1 ratio whether the timing device is initially activated or is acknowledged through the use of the reset initiation devices.

Warning period timing and pulse circuits The warning period timing and pulse circuits generally indicated at 32 on FIGS. l and 2 of the drawings include the circuits shown immediately to the right of the inner lamp pulse circuits previously described. Resistor 152 is connected between lead 71 and base two of an unijunction transistor 153. The base one of this unijunction transistor is connected to one side of the primary winding of a transformer 154 having a secondary winding 1548. The other side of the primary winding is connected to lead 7'7. A potentiometer 155, a resistor 156 and a capacitor 157 are connected in series between lead 71 and lead 77. The emitter of the unijunction transistor 153 is connected between the resistor 156 and the capacitor 157 and to the anode of diode 158. The cathode of the diode 158 is'connected to one side of resistor 159 and to the emitter of transistor 160. The other side of resistor 159 .is connected to lead 71 while the collector of the transistor 160 is connected to the lead 77. The base of transistor 160 is connected to one side of resistor 161 and the other side `of the resistor 161 is connected to the anodes of diodes 162 and 163. The cathode of diode 162 is connected to the lead 91 and to the contact 92 of pressure switch 31. The cathode of diode 163 is connected by lead 164 to a terminal point 165 and the connections from this terminal point to other parts of the circuits will be described later.

The operation of the Warning period timing and pulse circuits will now be described. The capacitor 157 charges up through a total equivalent resistance equal to the series resistance sum of the potentiometer 155 and -resistor 156 until the potential of the positive plate of capacitor 157 reaches the peak point voltage of the emitter of the transistor 153. When this occurs, the unijunction transistor 153 turns `on and discharges the capacitor 157 through the primary winding of transformer 154. This produces `a sharp rise-time pulse in the secondary winding 154S of the transformer 154 shown associated with the other circuits near the center lower portion of FIG. 2, and the operation of these circuits will be discussed later.

Base two resistance of unijunction transistor 153 is provided by resistor 152 which is of the proper value to provide temperature compensation of transistor 153 at the operating voltage of 28 volts. The potentiometer 155 can be adjusted to provide any desired length of warning period, as for example, 5 to 30 seconds.

The timing and pulse generation sequence ofthe warning period timing and pulse circuits can be interrupted by the operation of the transistor 160 and associated circuitry. If, for example, the cathodes of either diode 162 or diode 163 are grounded through the pressure switch 31 or other circuits connected lto the terminal 165, the transistor 165 is turned on with the collector current of transistor 168 being limited by the resistor 159. The -emitter potential of transistor 160 then falls from 28 voltsl toward slightly above ground potential and diode- 158 clamps the positive plate of capacitor 157 to this same potential. This stops the periodic pulse generating operation of the unijunction transistor 153. If the cathodes of the diodes 162 and 163 are not grounded, the transistor 160 is turned off and the unijunction transistor 153 and associated circuitry operate as previously described.

The grounding of the cathodes of diodes 89, 103 and 162 occurs if a brake application of suicient magnitude is` made by the locomotive engineer at any time when the outer lamp pulse circuits, the inner lamp pulse circuits, and the Warning period timing and pulse circuits are operating. When a brake application is made the reduction in brake system air system air pressure causes the pressure switch 31, with normally open contacts 92 land 93, to close and connect lead 91 from the cathodes of diodes 89, 103 and 162 to ground or the negative terminal of the battery. When this occurs there is a cessation of the progressive lamp illuminations around both the outer circle of lamps 16 and the inner circle of lamps so that only the particular lamp or lamps that were illuminated at the instant the pressure switch was activated remain illuminated. The release of the locomotive brakes at some future time then reactivates the pulse circuits 27, and 32 and the illuminated lamp sequence continues from the point where it left olf until the completion of the timing cycle.

At this point it should be noted that all three of the timing and pulse generation circuits, namely the outer lamp pulse circuits 27, the inner lamp pulse circuits 25 and the warning period timing and pulse lcircuits 32 start operating as soon as the 28 volt supply voltage becomes available lfrom the semi-regulated voltage supply 12. Unless the cathodes of the appropriate diodes 89, 9i),

1112, 1613, 1114, 162 and 163 are grounded in some manner, periodic timing pulses will appear at the output of the secondary windings 8451, 84S2, 1185 and 1548 of the respective transformers 84, and 154.

Ring counter 21 The circuits for the ring counter indicated at 21 on FG. 1 are shown in detail in the upper half of FIG. 3. The ring counter is a twelve stage counter, but as the stages are identical the circuit diagram has been broken between stage 5 andstage 9. The individual lamps 18 of the outer circle of lamps 16 are shown in FIG. 3, and there are twelve individual lamps as shown on FIG. 1 of the drawings.

Power is furnished to the circuits of the ring counter 21 through the positive terminal 70 of the semi-regulated D.C. power supply 12 and through the lead 166. The negative or ground terminal of the power supply is connected to one side of the air core inductor 131 in the ring counter.

While a plurality of the stages of the ring counter have been shown in association with their corresponding lamps 18, it can be seen that each of these stages is of similar design so it is believed suicient to identify and describe the arrangement of several associated stages. Considering the irst stage shown at the left-hand portion of the outer ring counter 21, it can be seen that there is a resistor 167, one side of which is connected to lead 166 and the other side of which is connected to the anode of the silicon controlled rectifier 168. Another resistor 169 is -connected between lead 166 and one side of the lamp 18. The other side of the lamp is connected between the resistor 167 and the anode of silicon controlled rectier 168 and also to one side of resistor 170' and one plate of capacitor 171. The other plate of the capacitor 171 is connected to the negative or ground terminal of the power source. The purpose of the resistor 169 is to reduce the 28 volt D.C. potential to the required lamp potential.

The cathode of the silicon controlled rectiiier 168 is connected to lead 172, and this lead 172 provides a common lead for connection of the cathodes of all the silicon controlled rectiiers in the outer ring counter 21. The air core inductor 131 is connected between lead 172 and the negative or ground terminal of the power supply.

The ring counter 21 is directly connected to the ring counter 19 through lead 173 shown at the left-hand side of FIG. 3, and through lead 174 shown at the righthand side of this ligure. Lead 173 runs to terminal point 175 and the connections to this point will be described later in conjunction with the description of ring counter 19. Diode 176 is in lead 173` and the cathode of this diode is connected to one side of resistor 177. The other side of this resistor is connected to a terminal point 178.

Lead 174 connects the anodes of diode 179 in ring counter 21 and diode 180 in ring counter 19. It should be pointed out at this point that a secondary winding 14652 of the transformer 146 is shown at the central righthand section of FIG. 3, and it will be recalled that the other secondary winding 14681 of this transformer 146 was previously discussed in conjunction with synchronizing circuits between the outer and inner lamp pulse circuits. This secondary winding 14682 is connected at one side to ground and at the other side to resistor 181. The resistor 181 is in turn connected to the lead 174.

Referring again to the upper left-hand portion of FIG. 3, diode 182 is shown connected in lead 129 with the cathode being connected to the terminal point 178. One side of a resistor 183 is connected to this terminal point 178 and the other side to a lead 184 that terminates at terminal point 185 near the right-hand side of FIG. 3. Another diode 186 also has its anode connected to lead 129 and its cathode connected to one side of the resistor 187 and to one plate of capacitor 188. The other side of the resistor 187 is connected through lead 189 to a terminal point 196 shown to the right of terminal point '13 185. One plate of capaictor 191 is connected to the terminal point 178 while the other plate of this capacitor 191 is connected to the gate of the silicon controlled rectifier 168, a plate of capacitor 188, and one side of resistor 192. The other side of the resistor 192 and the cathode of the silicon controlled rectifier are connected `to the lead 172.

The anode of a diode 193 is connected to lead `1.29 and the cathode of this diode is connected to one side of the resistor 170 and one plate of a capacitor 194. The other plate of the capacitor 194 is connected to the gate of a silicon controlled rectifier 195 and to one side of a resistor 196. The cathode of the silicon controlled rectifier 195 and the other side of the resistor 196 are connected to the lead 172. The anode of silicon controlled rectier 195 is connected to one side of resistor 197 and the other side of this resistor 197 is connected through lead 166 and to the positive terminal of the power supply of 28 volts shown as terminal 70.

It is not thought necessary at this time to further label the electrical components of the circuits associated with the twelve lamps, 18, of the ring counter circuit 2|1 because it can be seen that each of the lamps 18 is associated with circuits similar to those just described. However, it should be noted that at the upper right-hand side of FIG. 3 there is a lamp 198, the function of which will be described later, and this lamp is in series with a resistor 199 and a capacitor 200 between lead 1616 and the ground or negative terminal of the power supply. This lamp 198 can be located on the indicator lamp panel 14 as shown in FIG. l. There is a resistor 201 connected between lead 166 and terminal point 190, previously mentioned, and a connection between this terminal point 190 and the anode of a silicon controlled rectifier 202. Terminal point .190 is also connected between lamp 198 and capacitor 200. The cathode of diode l179 is connected to the gate of the silicon controlled rectier 202 and to one side of a resistor 283. The other side of the resistor 2013 and the cathode of the silicon controlled rectifier are connected to lead 172.

At the left center portion of FIG. 3, one side of the secondary winding 84S2 of transformer 84 is shown connected to resistor 204. The other side is connected to one side of resistor 205 and-tok ground. The other side of the resistor 204 is connected to the anode of a diode 206, and the cathode of diode 206 is connected to terminal point 207. The other side of the resistor 205 is also connected to terminal point 207. Capacitor`132 is 'the lower left-hand portion of FIG. 2. There is also 'a connection between the terminal point 207 and a terminal point 2110, which terminal point 210 is also shown at the left-hand portion of FIG. 2. The operation of the circuits in the ring counter 21 and associated circuits in the timing device will be discussed at some length later after a description of the circuits of the ring counter 19.

Ring counter 19 At this point attention is directed to the lower portion of FIG. 3 where the circuits of the ring counter 19 are shown. In the circuit diagram shown on FIG. 3, the circuits have been broken as indicated because as in the case 'of the ring counter 21, the circuits associated with each of the lamps 17 are the same, and it will be understood that the complete circuit for the ring counter 19 will include circuits for each of the twelve lamps 17 found in the inner lamp circle 15. As was done in the description -of the circuits of the ring counter 21, only some of the components of the circuit will be labelled and described,

as it is not believed necessary 'to' completely label each of the components in the identical circuits associated with each of the lamps 17. y

Terminal 70 is the positive terminal of the power supply and is connected to lead 21:1 to furnish 28 volts direct current to the ring counter 19 and the negative or ground terminal of these circuits is connected to one side of the air core inductor 212 and to one side of the resistor 213. The other side of the air core inductor 212 is connected to a lead 214 to which each of the cathodes of the twelve silicon controlled rectifiers for each lamp circuit is connected. The other side of the resistor 213 is connected to lead 215.

Referring to the left-hand portion of FIG. 3, the anode of diode 216 is shown connected to lead 215 and the cathode of this diode is connected to one plate of capacitor 217 and one side of resistor 218. The other side of resistor 218 is connected through lead 2419 to a terminal point 220, shown at the right-hand side of the tigure, and the connections from this terminal point will be explained later. The other plate of the capacitor 217 is connected to the gate of the silicon controlled rectier 212-1 and to one side of resistor 222. The other side of the resistor 222, as well as the cathode of the silicon controlled rectier 2211, are connected to lead 214.

The anode of the silicon controlled rectier 221 is connected to one side of resistor 223 and to a terminal point 224. The other side of the resistor 223 is connected to one side of resistor 225 and to lead 211. Resistor 225 is designed to reduce the voltage applied to the lamp 17 and is connected to this lamp and to a lead 2.26 associated with each of the lamps 17 in the circuit. Lamp 17 is also connected to terminal point 224 as is one plate of capacitor 227 and one side of resistor 228. The other plate of the capacitor 227 is connected to ground and the other side of the resistor 228 is connected to the cathode of a diode 229 land to one plate of capacitor 230. The anode of diode 229 is connected to lead 215 and the other plate of the capacitor 230 is connected to the gate of silicon controlled rectier 231 and to one side of resistor 232. The other side of the resistor 2132 and the cathode of the silicon controlled rectier 231 are connected to the lead 214.

Turning to the right-hand section of the circuits for the ring counter 19, a lamp 233 is shown connected in series with a resistor 234and a capacitor 235. This lamp can be located on the lamp indicator panel 14 shown on FIG. 1 of the drawings. The capacitor 23'5 is grounded to the negative terminal of the power supply while the resistor v234 is connected to lead 211 and to the positive terminal of the power supply at 70. Lead 211 is also connectedy to resistor 236 and the other side of resistor 236 is connected to terminal point 220 as is the connection between the lamp 233 and the capacitor 235. The anode of silicon controlled rectifier 237 is connected to terminal point 220, while the cathode of this silicon controlled rectier is connected to lead 214. The gate of the silicon controlled rectifer 237 is connected to resistor 238 and to the cathode of diode 180. The other side of the resistor 238 is likewise connected to the lead 214.

The secondary winding s of the transformer d10, previously mentioned, is shown at the lower left-hand corner of FIG. 3, and it can be seen that one side of this secondary winding Iis grounded and is connected to one side of resistor 239. The other side of the resistor 239 leads to a terminal point 240. The other side of the secondary winding 1108 of transformer 110' is connected to a resistor 241 and the other slide of the resistor 241 is connected to the anode of diode 242. The cathode of the Adiode 242 is connected to the terminal point 240 and capacitor 243 is connected between terminal point /240 and the lead 215. There is also a connection to the terminal point 240 from one side of the resistor 244 and the other side of the resistor 244 is connected yto the cathode of diode 245. The anode of the diode 24S is connected to terminal point 165, previously mentioned in conjunction with the circuits of ring counter 21.

When the timing device is initially turned on, 28 volts direct current is applied to the circuits of the ring counters 19 and 21 and initially each of the silicon controlled rectifiers in the two ring counters are turned off and none of the lamps 17, i18, 198 and 233 are energized. However, when the safety .reset device 36 is momentarily activated by the locomotive engineer, the silicon controlled rectifier 246, shown in the lower left-hand portion of FIG. 2, is-turned on by means of a network which will be described later. When the silicon controlled rectifier 246 is turned on, the anode voltage of this -rectifier drops to slightly above ground potential which removes the direct current bias at the terminal point 165 from the network composed of diode 206,

capacitor 132, resistor 208 and diode 209 shown associated rwith the ring counter 21 and from the similar network of ring counter 19. This same momentary acti'vation of the safety reset device 36 also causes -a current fiow in the primary wind-ing of transformer 146 through capacitor 143, resistor 144 and diode 145. This in turn causes a positive pulse to appear in the secondary winding 14682 of the transformer 146 shown at the central right-hand portion of FIG. 3. This pulse passes through .the resistor 181, then through the diode 179 into the gate circuit of the siliconcontrolled rectifier 202 and turns this rectifier on. This allows a current iiow through the lresistor 201 and energizes the lamp 198.

When the silicon controlled rectier 202 is turned on, the anode voltage of the rectifier is slightly above ground potential and thus removes the direct current bias from the network composed of diode 186, capacitor 188 and resistor 187. The first positive pulse occurring in the secondary winding 8452 of the transformer 84 due to the operation of the outer lamp pulse circuit 27, previously described, passes through resistor 204, diode 206, capacitor 132 and to the lead 129. Since the direct current bias at the junction of diode 186, capacitor 188 and resistor 187 was removed when the silicon controlled rectifier 202 was turned on, the positive pulse continues through diode 186 and capacitor 188 into the gate circuit of the` silicon controlled rectifier 168 and turns it on. .This allows a current flow through the resistor 167 and energizes the first lamp 18. It should be noted that this particular positive pulse also appears simultaneously at the anodes of al1 the pulse input -diodes of the various stages of the ring counter 21, but that all of the diodes except diode 186 are reverse biased by their respective interstage coupling networks, and in each 'case this direct current voltage bias originates at the anodes of the preceding silicon controlled rectifier stages since all of these silicon controlled rectifiers are turned off. Thus, the positive pulse from the outer lamp pulse circuits 27 is blocked from the gate circuits of all of the silicon controlled rectifiers in the ring counter 21 except the gate circuit of silicon controlled rectifier 168.

When the silicon controlled rectifier 168 turns on, several events occur. First, the anode to cathode current flowing in the rectifier 168, which is the sum of the currents through resistor 167 and larnp 18, passes through the lead 172 and the air core inductor 131 to ground. This causes a positive voltage transient to appear at the top connection of` the inductor 131, which, in conjunction with the operation of the capacitor 200, reverse biases-theV silicon controlled rectifier 202 so that it turns off, thus de-energizing the resistor 201 and extenguishing the ylamp 198.

Secondly, with the s-ilicon controlled rectifier 168 turned on,-its anode potential is slightly above ground, and therefore the direct current voltage bias on ,the interstage coupling network, composed of the ydiode 193, capacitor 194 and the resistor 170, is removed. This prepares the second stage, including the silicon controlled rectifier 195 and the second lamp 18 in the ring counter l@ 21 for activation when the next positive pulse is received at the anode of diode 193.

Thirdly, when the silicon controlled rectifier 202 is turned off as the result of the turn on of silicon controlled rectifier 168, the direct current Voltage bias to the `diode 186, capacitor 188 and resistor 187 network is restored and this prevents any following positive pulses appearing at the anode of diode 186 from reactivating silicon controlled rectifier 168.

The second positive pulse appearing in the secondary winding 84S2 of the transformer 84 as the result of the operation of the outer lamp pulse circuits 27 will activate the silicon controlled rectifier through diode 193 and silicon controlled rectifier :168 is turned off. In a manner described in the preceding paragraph, the circuits associated with the next silicon controlled rectifier 247 are prepared to receive the following positive pulse to be delivered to the ring counter circuit 21. This process continues repetitiously for positive pulses three through eleven, respectively, until finally the twelfth positive pulse turns on the silicon controlled rectifier 248. At this time all of the other silicon controlled rectifiers in the ring counter circuits 21 are turned off.

When the silicon controlled rectifier 248i is turned on, its anode .potential will be slightly above ground and the direct current bias is removed from the network composed of diode 182, capacitor 191 and Iresistor 183. It should also be noted that there is a secondy source of direct current bias for this network originating at the anode of the sixth stage silicon controlled rectifier 249 of the ring counter 19 shown at the lower portion of FIG. 3. This voltage bias passes through lead 173, diode 176 and resistor 177 to the terminal point 178. Since the ring counter 21 advances from stage to stage at a rate that is twice that of the ring counter 19, it is evident that when silicon controlled rectifier 248 is activated for the first time, the silicon controlled rectifier 249 will also be activated. Since the anode potential of the silicon controlled rectifier 249 under these conditions is also slightly above ground, the three-way junction point or terminal 178 is unbiased and the thirteenth positive pulse appearing at the anode of diode 182 from the secondary winding 8482 of transformer 84 will pass through this diode 182, .capacitor 19'1, and into the gate circuit of silicon controlled rectifier 168 to turn it on for the start of the second cycle of operation of this ring counter 21.- It s'hould be particularly noted that this second cycle of operation of ring counter 21 can only be initiated under the conditions in which both the silicon controlled rectifier 248 and silicon controlled rectifier 249 are turned on.

The fourteenth positive pulse from pulse circuits 27 then turns on silicon controlled rectifier 195 and turns off silicon controlled rectifier 168, as previously eX- plained. This process continues for positive input pulses Nos. fifteen through twenty-three, respectively, until silicon controlled rectifier 248 is once again turned on by positive pulse twenty-four. Under these conditions only silicon controlled rectifier 248 and silicon controlled rectifier 250 in the ring counters 21 and 19, respectively, are turned on. Although the silicon controlled rectifier 248, when turned on, removes the source of direct current bias from one end of resistor 183, the silicon controlled rectifier 249 isv still turned off and supplies a direct current voltage bias to one end of resistor 177. This causes the diode 182 to remain reverse biased and, although more positive input pulses continue to occur at the anode the diode 182 to remain reverse biased land, although turn on. Under these conditions, silicon controlled rectifier 168 will not turn on. Under these conditions, sil-icon controlled rectifier 2:48 remains turned on indefinitely until some future time when the reactivation of the silicon controlled rectifier 202 sets up the network cotrn posed of diode 186, capacitor 188 and resistor 187 so that a .positive input pulse can turn on the silicon controlled rectifier 168 and restart a new timing cycle.

trolled rectifier 248 via resistors 183 and 177 to the anode of the silicon controlled rectifier 249, which under certain conditions could cause malfunctioning of the circuits. used to prevent any voltage feedback from the terminal point 207 to the terminal 165 and the anode of the silicon controlled rectifier 246 shown on FIG. 2. The resistors shown at 205 and 130 are bleeder resistors and are used in the interval between pulses from the secondary Winding 84S2` of transformer 84 to remove any residual charges remaining on both plates of the capacitor 132.

The operation of the ring counter 19 involves the application of the 28 Volt direct current to the circuit, and initially all the silicon controlled rectifiers in the ring counter 19 are turned off and none of the lamps 17 in the circuit is energized.

As previously discussed, the momentary activ-ation of the safety reset device 36 turns on the silicon controlled rectifier 246 and removes the direct current voltage bias at terminal 165. It should be noted that this bias point 165 is common to both the ring counter 19 and ring counter 21. At this same time a positive pulse appears lin the secondary winding 146S2 of the transformer 146 and this pulse passes through the resistor 181, through lead 174 to diode 180 and into the gate circuit of the silicon controlled rectifier 237 to turn this rectifier on. This allows a current fiow through resistor 236 and energizes lamp 233. y

When the silicon controlled :rectifier 237 is turned on, the anode voltage of this rectifier is slightly above ground potential thus removing the direct current bias from the network composed of diode 216, capacitor 217 and resistor 218. The first positive pulse occurring in the secondary winding 110s of the transformer 110 due to the operation of the Iinner laimp pulse circuits 25 passes through the resistor 2.41,` diode 242, capacitor 243 and to the lead 215 connecting al1 of the anodes of the diodes associate-d with the various stages of the ring counter. Since the direct current bias at the junction of diode 216, capacitor 217 and resistor 218 was removed when the silicon controlled rectifier 237 was turned on, this input pulse continues through diode 216 and capacitor 217 into the gate circuit of the silicon controlled rectifier 221 to turn it on. This permits a current fiow through resistor 2213 Iand energizes the first timing lamp 17. It should be noted that this particular input pulse also appears at the anodes of all the pulse input diodes of the various stages of the ring counter 19, but all of these diodes are reverse biased by their respective interstage It is for the same reason that the diode 209 is coupling networks, and in each case this direct currenty voltage bias originated at the anodes of the preceding silicon controlled rectifier stages since all of these silicon controlled rectifiers afre turned ofi. Thus, the first positive input pulse is blocked from the gate circuits of all of the silicon controlled rectifier stages in the ring counter 19 except the silicon controlled rectifier 221.

When silicon controlled rectifier 221 turns on, several events occur. First, the anode to cathode current fiowing through rectifier 2211, which yis the sum of the currents through resistor 2-23 and lamp 17, passes through lead 214 and the inductor 212 to ground. This causes a positive voltage transient to appear at the top connection of inductor 212, which, in conjunction with the operation of the capacitor 235, reverse biases the silicon controlled rectifier 237 so that it turns off, thus de-energizing resistor 236 and extinguishing lamp 233.

Secondly, with the silicon controlled rectifier 221 turned Ion, its anode potential is slightly above ground so that the direct current voltage bias on the interstage coupling network composed of diode 229, capacitor 230 and resistor 228 is removed. This prepares the second stage in the ring counter 19 for activation when the next posi- 18 tive input pulse is received -at the anode of diode 229.

Thirdly, when the silicon controlled rectifier 237 is turned off, a direct current voltage bias is restored to the network consisting of diode 216, capacitor 217 and resistor 218, thus preventing any following positive input pulses appearing at the anode of diode 216 from Ieactivating silicon controlled rectifier 221.

The second positive input pulse appearing in the secondary winding S of transformer 110 from pulse circuits 25 activates the silicon controlled rectifier 231, which turns off silicon controlled rectifier 221 and prepares the following silicon controlled rectifier in the next stage for the next positive input pulse. This process co-ntinues repetitively `for input pulses Nos. three through eleven until finally the twelfth input pulse turns on silicon controlled rectifier 250. At this time all of the other silicon controlled rectifiers in the `ring counter 19 are turned ofi', and under these conditions, rectifier 250 remains turned on indefinitely until some future time when the reactivation of the silicon controlled rectifier 237 sets up the network composed of `diode 216, capacitor V217 and resistor 218 so that the next positive input pulse can turn on the silicon controlled rectifier 221 and restart a new timing cycle.

Diode 245 is used to prevent any voltage feedback from the terminal point 240 tothe terminal which, under c'ertain operating conditions, could cause malfunctioning of the circuits. The resistors 239 and213 are bleeder resistors and are used to remove residual charges on the plates of the capacitor 243.

Warning circuits The circuits involved in the warning circuits 39 are shown at the lower left-hand portion of FIG. 2. A siliconcontrolled rectifier indicated at 251 has its cathode connected to the ground or negative terminal of the power supply and its anode connected to one plate of a capacitor 252, and a terminal point 253. The other plate of the capacitor 252 is connected to the terminal 165, previously discussed. Diode 254 and parallel resistor 255 are connected in series with a capacitor 256 between terminal point 253 and terminal point 95.

Lamp 43, a solenoid coil 257, a diode 258 and a resistor 259 are all connected in parallel between the second terminal .point 253 and the lead 137 running to the positive terminal of the power supply for the timing device. The lamp 43 has a resistor 260 in series therewith to provide for the correct voltage for the lamp.

As shown at the extreme lower left-hand corner'of FIG. 2, a secondary winding 8481 of transformer 84 is connected to resistor 261 .and to the ground terminal of the device. The resistor 261 is connected to the anode of diode 262 and th'e cathode of this diode is connected to terminal point 263. A resistor 264 is connected Ibetween terminal point 263 and ground and the cathode of a diode 265 is also connected to this terminal 263. The anode of the diode 265 is connected to terminal 210, and it will l.be recalled that this terminal is associated with the circuit arrangement for the outer ring counter 21 shown on FIG. 3.

A capacitor 266 is connected b'etween terminal 263 and terminal 267. A resistor 268 is connected between terminal 267 and the ground terminal, and the cathodes of diodes 269 and 270 are likewise connected to terminal point 267. The anode of diode 269 is connected to a resistor 271 and the other side of this resistor is connected to terminal which, it will be recalled, is associated with the anode of the silicon controlled rectifier 248 in the ring counter 21, as shown on FIG. 3. The anode of diode 270 is connected to resistor 272 and the other side of this resistor is connected to terminal 273. Terminal 273 is vshown connected to the anode of the silicon controlled rectifier 250 of the ring counter 19 on FIG. 3. Referring again to FIG. 2, one plate of capacitor 19 274 is connected to the terminal 267 and the other plate of this capacitor is connected to the gate of silicon controlled rectifier 251 and to one side of the resistor 27.5 which is grounded to the negative terminal of the power supply.

Silicon controlled rectifier 246, previously mentioned, has its cathode connected tothe ground terminal of the circuit and its anode is connected to the terminal point 165 and through lead 276 to another terminal Vpoint 277. A lamp 278 with associated resistor 279, diode 280 and resistor 281 are connected in parallel between terminal 277 and lead 137 to the positive terminal of the power supply. This lamp 278 can be mounted on the indicator lamp panel 14 or at any other suitable location in the locomotive cab. The gate of the silicon controlled rectifier 246 is connected to resistor 282, the cathode of diode 283 and a plate of capacitor 284. The yresistor is connected to ground and the other plate of capacitor 284 is connected to a terminal point 285. t Resistor 286 is connected between terminal point 285 and ground. The anode of the diode 283 is connected through a resistor 287 to a terminal point 288 and the connections to this terminal 288 will be discussed later. Resistor 289 is connected in series between terminal point 285 and a terminal point 290and the connections to this terminal point 290 will also be discussed later. A diode 291 and a resistor 292 are connected in series between terminal 285 and one plate of capacitor 143 shown 'at the right-hand side of FIG. 2.

From the circuit ararngements just discussed, it can be seen that if the silicon controlled rectifier 251 is turned on that the lamp 43 will be energized and the solenoid coil 257 will also be energized to sound a buzzer or Whistle. The diode 258 which is associated with the solenoid 257 is designed to suppress inductive voltage transicnts generated by solenoid 257 Whenever the silicon controlled rectifier 251 turns off.

Considering the gate circuitry of the silicon controlled rectifier 251, it can be seen that there are two separate networks in series and the first is composedof the diode 265, diode 262, capacitor 266 and resistor 264. The direct current voltage bias appearing at the anode of diode 2651is taken from terminal 210, and this terminal 210 is connected to the terminal point 207 in the circuits associated with the ring counter 21, as illustrated on FIG. 3. Since thedirect current voltage bias at this point 207 is actually derived 'from the anode of the silicon controlled rectifier 246 or the terminal point 165 as shown both on FIGSfZ and 3, it is evident that the direct current voltages bias appearing at the terminal point 263 will be present when the silicon controlled rectifier 246- is turned off and Will be absent when this silicon rectifier 246 is turned on.

If a direct current voltage bias is present at the terminal point 263, this bias voltage causes current to flow from the anode of the silicon controlled rectier 246 or terminal point 165 through diode 209, resistor 2018, diode 265 and resistor 264to ground. As a result, the diode 262 is reverse biased and will not conduct when positive pulses appear at its anode lfrom the secondary winding 84S1 of the transformer 84.

There is a second network composed of the resistor 271, diode 269, capacitor 266, capacitor 274 and resistor 268 and the parallelvarrangement of resistor 272, diode 270 and the capacitors 266 and 274 and resistor 268. The direct current voltage bias which appears at the upper terminal of resistor 271 is taken from terminal 185 associated with the anode of the silicon controlled rectifier 248 in the ring counter circuit 21. The direct current voltage bias appearing at the upper terminal of the resistor 272 is taken from the terminal 273 which is associated with the anode of the silicon controlled rectifier 250 of the ring counter 19. If the silicon controlled rectifier 248 is turned off, current fiows from the anode of this silicon controlled rectifier through terminal 185,

through resistor 271, diode 269 and resistor 268 to ground. Likewise, if the silicon controlled rectifier 250 is turned off, current flows from the anode of this silicon controlled rectifier to terminal 273, through resistor 272, diode 270 and the resistor 268. In either case, the current flow through the resistor 268 to ground causes the right-hand plate of capacitor 266 and the left-hand plate of capacitor 274 to become positively charged. Under these conditions, any positive pulse appearing in the left-hand plate of capacitor 266 will be blocked and thus prevented from passing through capacitor 266 and capacitor 274 to the gate of silicon controlled rectifier 251.

From the above discussion it should V'be evident that the direct current voltage bias appearing at the terminal point 267 will be abs'ent only when both `silicon controlled rectifiers 248 and 250 are turned on, and this will occur only at the end of the period during which the outer circle of lamps 16 will have completed two cycles of lamp energization and the inner circle of lamps 15 will have been energized for one cycle.

When positive pulses appear in the s'econdary winding 84S1 of the pulse transformer 84 they pass throughy resistor 261 and diode 262 to the terminal 263. If the silicon controlled rectifier 246 is turned on, terminal and terminal 263 Will be slightly above .ground potential. Thus, the direct current voltage bias is removed from this terminal 263 and the positive pulses can pass through capacitor 266 to the terminal point 267. If both the sili con controlled rectifiers 248 and 250 are turned on, then terminals and 273 are each slightly above ground potential, This removes the direct current voltage bias Brom the terminal 267 and the positive pulses can continue through capacitor 274 to the gate of the silicon controlled rectifier 251 to turn this rectifier on.

The lamp 278 is energized when the warning lamp 43 and the .signal associated with the solenoid 257 have been de-encrgized. Referring to the silicon controlled rectifier 246 which activates the load resistor 281 and the lamp 278 when the rectifier is on, it can be seen that there are two separate circuits through which pulses can arrive at the .gate or the rectifier 246 and turn it on. In one case, a positive pulse appearing at the Vjunction 288 will pass through the limiting resistor 287 and diode V283 into the gate of the silicon controlled rectifier 246 to turn this rectifier on. In the second case, a positive volta-ge appearing at the right-hand plate of capacitor 143 causes current to pass through the limiting resistor 292, diode 291, to the terminal 285 and through the resistor 286 to ground. If the silicon controlled rectifier 293, which will be described later, is turned on, there is no direct current voltage bias applied by means of resistor 289 to the terminal point 285 and therefore, no potential drop across the resistor 286'resulting from current fiow through resistor 286 to ground. Th'erefore, any positive voltage pulse appearing at the right-hand plate of the capacitor 284 is coupled into the gate circuit of silicon controlled rectifier 246 and this rectifier is turned on. It should be noted that if the silicon controlled rectifier 293 is turned off, the steady state current fiow from the anode of the silicon cont-rolled rectifier 293 through resistor 289 and resistor 286 to ground causes the diode 291 to become reverse biased, thus preventing the turn on of silicon controlled rectifier 246 when voltage is applied to the anode of the diode 291.

Action circuits and brake solenoid valve circuits The circuits involved in the action circuits 40 are shown at the lower central portion of FIG. 2 and include the silicon controlled rectifier 294 which operates in conjunction with the brake solenoid valve circuits 41. Th-esilicon controlled rectifier 294 has a gate circuit including r'esistor 295 and diode 296. The cathode of the silicon controlled rectifier 294 is connected to the lead 147 and to the negative terminal of the power supply. A resistor 297 is connected from the gate of the rectifier 294 to the lead 147. Resisto-r 298 and capacitor 299 are connected in series between the anode and the cathode of the silicon controlled rectifier 294. The resistor 298 and the capactior 299 are so conrfected in order to minimize the rate of rise of applied voltage effects which might cause the silicon controlled rectier 294 to turn on prematurely when the timing device is initially turned on.

The indicato-r lamp 45 with associated resistor 300 is connected between terminal 95 and terminal 301. A solenoid coil 302, a diode 303 and resistor 304 are connected to the anode of silicon controlled rectifier 294 through terminal point 95 and to the positive terminal of the power supply through terminal 301 and lead 137.

The brake solenoid valve circuits 41 are shown in conjunction with the silicon controlled rectifier 293. The cathode of the silicon controlled rectifier 293 is connected to lead 147 and the anode is connected to terminal 290. A resistor 305 is connected between the gate of the rectifier and the lead 147 and there is also a diode 306 and resistor 307 connected in series between the gate of the rectifier 293 and the terminal point 283. esistor 308 is connected between terminal 288 and lead 147 and one plate of capacitor 309 is also connected to the terminal 288. The other plate of capacitor 309 is connected through resistor 310 to lead 147 and through lead 311 to the contact 138 of the safety reset device 36 and to the f anode of diode 139.

Lamp 47 with associated resistor 312, solenoid coil 313, diode 314 and resistor 315 are all connected in parallel between the terminal 290 and the lead 137 going to the positive terminal of the power supply. Capacitor 316 is connected between terminal .point 95 and terminal point 290. The solenoid 313 is associated with the brake solenoid valve, shown -generally at 52 on FIG. 1 of the drawings.

The silicon controlled rectifier 293 can be turned on when a positive pulse appears at the terminal 288 and passes through the resistor 307 and diode 306 to the gate of the rectifier.

We now come to the mode of operation of the warning circuits 39, action circuits 40 and brake solenoid valve circuits 41 with the associated signal and valve means. Referring specifically to FIG. 2 of the drawings, when the timing device is initially turned on the power is applied to these circuits, but all of the silicon controlled rectifiers 251, 246, 294 and 293 remain turned off. If the safety reset device 36 is momentarily closed by the engineer, the following events will occur. A positive pulse will be delivered through lead 311, capacitor 309, resistor 307 and diode 306 to the gate of the lsilicon controlled rectifier 293 to turn this rectifier on. When the rectifier 293 is turned on, current will flow through the solenoid coil 313, the lamp 47 will lbe energized, and the anode voltage of silicon controlled rectifier 293 will fall to slightly above ground potential and thus remove the direct current vo-ltage bias applied to the gate circuitry of silicon controlled rectifier 246 via resistor 289.

The positive pulse which appears iat terminal 288 also passes through resistor 287 and diode 283 into the gate of silicon controlled rectifier 246 to turn this rectifier on. The turn o-n of rectifier 246 causes the activation of the lamp 278, and the anode potential of silicon controlled rectifier 246 will fall to slightly above ground potential. When the anode potential of silicon controlled rectifier 246 falls, the cathode of diode 163 is grounded and this stops the operation of the warning period timing and pulse circuits `32, as previously described. `The fall of the anode potential of silicon controlled rectifier 246 also removes the direct current voltage bias at the terminal 165 to thereby set up one of the conditions necessary to start the operation of both of the ring counters 19 and 21. This fall of anode potential at terminal 165 also removes the direct current voltage bias at terminal 210, in the manner previously described, and this unbiases 22 the pulse network through terminal 263 to the gate circuitry of silicon controlled rectifier 251.

A positive potential also appears at the right-hand plate of capacitor 143 because of the conduction of forward biased diode 139 and this the-n causes a positive pulse to appear at the junction of capacitor 143 and the resistor 318 which then passes through the resistor 144 and diode 145 into the primary winding of transformer 146. This causes a positive pulse to appear in the secondary winding 14652 of transformer 146, shown at the right-hand edge of FIG. 3, and this pulse will pass through resistor 181 and diode 17-9 into the gate of silicon controlled rectifier 202 which turns on this rectifier. This same voltage pulse will also turn on silicon controlled rectifier 237 by passing through diode into the gate circuitry of this rectifier. It will be recalled that this is one of the :conditions necessary to start the operation of both of the ring counters 21 and 19.

A positive potential appearing momentarily at the junction of capacitor 143 and the resistor 317 also causes a current to flow momentarily through resi-Stor 292, diode 291 and resistor 286 to ground. However, when the silicon controlled rectifier 293 was turned on as previously described, the voltage bias at the terminal 285 was removed and hence this current flow through the resistor 286 to ground causes another positive pulse to appear in the gate circuit of silicon controlled rectifier 246 to turn on this rectifier via a second circuit path. It should be noted that the pulses into the gate circuit of silicon controlled rectifier 246 via the two separate circuit paths probably reach the gate circuit of this rectifier almost simultaneously although the pulse via the diode 291 cannot pass through capacitor 284 until silicon controlled rectifier 293 has been turned on.

It should also be noted that if any of the reset initiation devices 34 had been momentarily activated instead of the safety reset device 36, only the step involving the positive pulse to the primary winding of transformer 146 and the resultant turn on of silicon controlled rectifiers 202 and 237 would have occurred. Thus, although silicon controlled rectifiers 202 and 237 would have turned on, silicon controlled rectifiers. 246 and 293 would have remained turned off. With silicon controlled rectifier 246 turned off, the ri-ng counters 19 and 21 could not have started operating because of the anode potential bias voltage at terminal 165. With the silicon controlled rectifier 293 turned off, the locomotive brakes would remain `applied Ias in a service application.

Assuming, then, that both the ring counters 19 and 21 have operated during a time period so that silicon controlled rectifier 248 of the ring counter circuits 21 and silicon controlled rectifier 250 of the ring counter vcircuits 19 have turned on, this removes the direct current voltage bias at both terminals and 273 with the result that the next pulse appearing in the secondary winding 8481 of pulse transformer 84 passes through resistor 261, diode 262, capacitor 266 and capacitor 274 into the gate of silicon controlled rectifier 251 and turns this'rectifier on. When the rectifier 251 is turned on, the following events will occur. First, the solenoid coil 257 will rbe activated to sound a suitable signal, such asma buzzer or whistle, and the warning lamp 43 will also be activated. Secondly, the silicon vcontrolled rectifier 246 will be turned off through the capacitor 251 and when the rectifier 246 is turned off, the lamp 278 will also be turned off. In addition, the turn off of the silicon controlled rectifier 246 results in the ungrou-nding of the diode 163 and starts the warning period timing and pulse circuits 32. Direct -current voltage bias is again established at terminal 165 which prevents any further operation of 'either of the ring counters 19 and 21 and the re-establish- 23 If no acknowledgement signal from the reset initiation devices 34 is received from the locomotive operator prior to the end of the warning period, ya positive pulse appears in the secondary winding 1548 of the transformer 154 due to the normal operation of the unijunction transistor 153 and its associated circuitry. This pulse passes through resistor 295 and diode 296 to the gate of the silicon controlled rectifier 294 and turns this rectifier on. When the silicon controlled rectifier 294 is turned on, the following events will occur. There will be an activation of the solenoid coil 302 to sound the action bell i) and the lamp 45 will be illuminated. The cathodes of diodes 90 and 192 will be Igrounded :and this will cause both the outer lam-p pulse circuits 27' and the inner lamp pulse circuits 25 to cease operation.

In addition, the silicon controlled rectifier 293 will be turned off by means of the capacitor 316 and when the silicon controlled rectifier 293 is turned off, the following will take place.. There will be a deactivation of the solenoid coil 313 which will cause the operation of the brake solenoid valve 52 and there will be a service application of the brakes of the train. The lamp 47 will also be turned off to indicate this condition. Furthermore, there will be a restoration of the -direct current voltage bias to the gate -circuits of the silicon controlled rectifier 246 through the resistor 289.

When silicon controlled rectifier 294 is turned off, the silicon controlled rectifier 251l will also be turned off through capacitor 256, diode 254 and resistor 255. It should `be noted at this point that the purpose of the diode254' and resistor 255 network is to provide a unidirectional comrnutation of the associated silicon controlled rectifers. As an example, in the situation Where silicon controlled rectifier 251l is conducting and the rectifier .294 4is blocking, the sudden turn on of the silicon controlled rectied 294 by means of its gate circuitry results in the turn off of the silicon controlled rectifier 251. If, however, the situation is reversed whereby the silicon controlled rectifiei 294 is conducting and the rectifier 251 is blocking, the sudden turn on of the rectifier 251 by means of its gate circuitry does not turn off the silicon controlled rectifier 294. From FIG. 2 it is evident that capacitors ,316 and 256 are connected in series between the anodes of silicon controlled rectifier 251 and silicon controlled rectifier 293. In the absence of the diode 254 and resistor 255 network, and in the case where the rectifier 293 is conducting and the rectifier 251 is blocking, as during the pre-warning period of the vdevices operation, the sudden turn on of the silicon controlled rectifier 251 at the start of the warning period will usually result inthe simultaneous turn off of the rectifier 293. This, of course, isfan undesirable mode of operation and is eliminated by'this diode and resistor network. The diode 254 will allow the high values of discharge current from capacitor 256 to pass in onlyk one direction and the resistor 255 will allow the left-hand plate of the capacitor 256k to charge up or bleed to ground, depending on Whether the rectifier 251 is blocking or conducting, respectively.`

When thegsilicon controlled rectifier 251 turns off, the solenoid coil 257 is deactivated and the lamp 43 is also deactivated.

As a result of the previously described operations, the silicon controlled rectifier 294 is turned on while silicon controlled'rectifiers 251, 246 and 293 are turned off. It should be pointed out that under these conditions, the warning period timing and pulse circuits 32 are operational `since the rectifier 246 is turned off and the cathode of diode 163 remains ungrounded. Periodic pulses will.

continue to be generated in the secondary winding 154S of the transformer 154 and this will insure that the silicon controlled rectifier 294 remains turned on.

The timing device will remain in this state indefinitely, with the locomotive brakes applied until some future time when the momentary activation of the safety reset device 36 will permit the locomotive engineer to release the locomotive brakes and restart the entire timing cycle over again in the manner previously explained.

1f an acknowledgment is made by the locomotive operator during the warning period by means of the momentary activation of the reset initiation devices 34, the direct current potential appearingat the junction of capacitor 143 and resistor 317 will cause the following events to occur. First, a positive pulse appears at the junction of capacitor 143 and resistor 318 which passes through resistor 144 and diode 145 into the primary winding of the transformer 146. This causes a positive pulse to appear in the secondary winding 14652 of the transformer 146 which activates the silicon controlled rectifiers 202 and 237 to reset the outer lamp pulse circuits and the inner lamp pulse circuits in a manner previously explained. There is also a momentary current flow from the junction of capacitor 143 and resistor 317 through resistor 292, diode 291 and resistor 286 to ground. Since silicon controlled rectifier 293 is still turned on, the direct current voltage bias fed to the terminal 285 is not present and this flow of current through resistor 286 to ground causes a positive pulse to appear at the gate of silicon controlled rectifier 246 and turn the rectifier on. When the rectifier 246 is turned on, the following events will take place. The lamps 278 will be activated, silicon controlled rectifier 251 will be turned off through the capacitor 252 and this results in the turn off of the solenoid coil 257 and the turn off of the lamp 43.

Also, when the silicon controlled rectier 246 is turned on, vthecathode of diode 163 is grounded which causes the warning period timing and pulse circuits to stop operating at some point in its timing period prior to the appearance of a pulse in the secondary Winding 154S of the transformer 154. In addition, when the rectifier 246 is turned on, the direct current bias voltage is removed from terminal 165 which then allows the ring counters 19 and 21 to start operating in a new cycle and the direct current bias voltage is also removed from terminal 210 so that the silicon controlled rectifier 251 can operate at the end of the newly initiated pre-warning period.

From the above sequence of events it is evident that when the timing device was acknowledged by the engineer or locomotive operator, it was reset such that a new timing cycle was initiated and since the silicon controlled rectifier 293 remained turned on, the locomotive brakes remained in a released condition.

If an acknowledgment signal is received from the locomotive operator -at any time during the pre-warning period by means of the momentary activation of the reset initiation devices 34, the direct current potential appearing at the junction of the capacitor 143 and resistor 317 causes a pulse in the secondary winding 14652 of transformer 146 to turn on or reset silicon controlled rectifiers 202 and 237 in the ring counters 21 and 19, respectively, in a manner previously described. At the same time, the silicon controlled rectifier 246 will be turned on and the results of this operation are the same as that previously described in conjunction with the acknowledgment of the locomotive operator during the Warning period. However, since the silicon controlled rectifier 246 is already turned on, the positive pulse into the gate of the silicon controlled rectifier 246 is redundant but actually does no harm. The turn on of the silicon controlled rectifiers 202 and 237 in the ring counter turns off the particular silicon controlled rectier in each ring counter that happens to be conducting at the instant the acknowledgment signal is received, and the ring counters then start a new timing cycle over again as previously explained.

It is apparent from lche above discussion that during any timing cycle of the timing device, the locomotive will travel a certain distance depending on the speed at which the locomotive is moving. Obviously, the potential hazards to the train and personnel increase with locomotive speed due to the fact that if the engineer becomes incapacitated or is inattentive for any reason, the train will continue its movement forward a greater distance before a brake application is initiated by the timing device. In order to prevent these dangerous situations, means have been provided to automatically shorten t-he timing cycle of the timing device with increased train speed so that the engineer must acknowledge the timing device at more frequent intervals and these means are described below.

Referring to FIG. 4 of the drawings, a block diagram of the basic extern-al speed control circuitry is shown associated wit-h a suitable locomotive axle drive. This locomotive axle drive can drive either a direct current generator 319 or an alternating current generator 320. If the generator is a direct current generator, the output is Iiiltered though filter 321 and delivered to the direct current voltage-to-resistance converter 322. If an alternating current generator 320 is used, the output of the generator is fed to a rectifier and filter shown at 323, and this output is then delivered to the direct current voltageto-resistance converter at 322. This converter 322 is designed to convert increasing direct current input voltage into a decreasing output resistance and is connected through terminals 81 and`82, shown at the upper middle portion of FIG. 2, in the outer lamp pulse circuits 27, previously described.

Referring to FIG. 5, one form of the voltage-to-resistance converter 322 is sh-own andthe circuit Iarrangement is such that there is a linea-r decrease in the output resistance to terminals 81 and 82 with a linear increase of the input voltage delivered by the axle driven generator and applied to the circuit through terminals 324 and 325. This arrangement includes the galvanometer movement 326 which is connected to terminals 324 and 325. This galvanometer movement is mechanically coupled to a linear taper potentiometer 327, and potentiometer 327 is connected to terminals 81 and 82. 'This type of converter can be used to provide means so that the timing device has a total timing period which charges in inverse proportion with an increasing locomotive or train velocity. Thus, for example, at higher speeds the locomotive engineer would be required to acknowledge the timing device at more frequent intervals than at lower speeds of the locomotive.

Referring to FIG. 6 of the drawings, another form of converter is shown, and this converter provides a nonlinear decrease of output resistance with a linear increase of input voltage. The input voltage is fed to an incandescent lamp 323 from the axle driven generator throughv terminals .329 and 330. The lamp 328 is associated with a photoresistor 331 and the photoresistor 331 is connected to terminals 81 and S2. As the lamp output increases with increased voltage, the resistance of the photoresistor 331 decreases in a non-linear manner. This type of non-linear volt'age-to-resistance converter can be used to provide a two-level timing rate for the timing device, as for example, one that operates at one rate below a predetermined locomotive speed, and at another rate above this same speed.

The circuits heretofore described for use in the timing device depend on solid state ring counters and pulse circuits with associated circuits for actuation of the alarms and b-rake application. These circuits have proved dependable and efficient but the invention is not limited to such electronic circuits. Another form of the invention is shown in FIG. 7 and illustrates the use of a stepping relay to provide for the sequential energiz-ation of the lamps 17 and 1-8 in the inner and outer circle of lamps and 16, respectively. This stepping relay is under the control of pulse circuits shown on FIG. 7 and the operation of the stepping relay in conjunction with these pulse circuits will now be described.

In order to simplify FIG. 7, only two decks of the stepping relay have been shown and these decks control the energization of lamps 17 and 13. However, it should be understood that other decks on the stepping relay can be used in an appropriate manner to actuate alarms and the brake solenoid valve associated with the timing device.

Referring now to FIG. 7, deck A of the stepping relay is indicated generally at 332, and immediately below this deck a second deck B of the relay is indicated generally at 333. The armature 334 for bothv decks is shown in dashed lines and is associated with the stepping relay coil 335 and with interrupting contact 336. The armature 334 carries contacts 337 and 338 which are associated with the stationary contacts 339 and 340 of decks A and B, respectively, in the stepping relay. Each of the decks A land B have twenty-four stationary contacts 339 Iand 340, respectively, but it should be understood that the number of contacts can be chosen to provide for any desired number of lamps 17 and 18.

Each contact 339 in deck A is connected to one side of any associated lamp 13 and each lamp has its other side connected to t-he negative terminal of the power supply. The positive terminal of the power supply is connected to contacts 337 and 338 on the armature. In order to simplify this figure, the circuits have been broken as indicated between the lamps three and ten in `deck A and in deck B. As thu-s shown, the lamp 18 adjacent the negative terminal of the power supply in deck A is the twelfth ylamp 18 in the outer ci-rcle of lamps 16. The remaining contacts 339 to the right of this lamp, namely the thirteenth through the twenty-fourth cont-act, are not all shown but the circuits have been broken between lamps fourteen and twenty-three in both deck A and deck B. The thirteenth through the twenty-fourth contacts 339 in deck A are connected -to the first through twelfth contacts, respectively, in this deck so that as the armature contact 337 moves across the complete set of contacts 339, each of the individu-al lamps 18 in the outer circle Iof lamps 16 will be energized twice.

Deck B differs from deck A only in that each lamp 17 is connecte-d t-o two adjacent contacts 340 so that as the contact 338 on armature 334 is progressively moved along through the action of the stepping relay coil 335, two lamps 18 will be energized for each lamp 17 that is energized. Thus, it is apparent that .the sequential energiza- Ition of lamps in the outer circle of lamps 16 will be at twice the rate as that of the lamps in the inner circle of lamps 15 in the manner previously described.

The stepping relay coil 335 is tied in parallel with an inductive surge protection diode 341 and the capacitor 342. These three elements are connected in series with the stepping relay interrupting Contact 336 and between the cathode of silicon controlled rectifier 343 and the negative terminal of the power supply. The anode of this silicon controlled rectifier is connected to the positive terminal of the power supply and to one side of resistor 344. The gate of the silicon controlled rectifier 343 is connected toV one side of a resistor 345 and to the cathode of diode 346. The other side of the resistor 345 is connected to the cathode of the rectifier 343 and to one side of the secondary winding of the pulse transformer 347. The anode of diode 346 is connected to the other side of the secondary winding of this transformer. y

Resistor 344 is connected to one side of resistor 348 and to one side of potentiometer 349. The other side of resistor 348 is connected to base two of unijunction pulse transistor 35@ and base one of this transistor is connected to one side of the primary winding of the pulse transformer 347. The other side of this primary winding is connected to the negative terminal of the power supply. Resistor 351 and capacitor 352 are connected in series between one side of the potentiometer 349 and the negative terminal Aof the power supply. The emitter of the transistor 350 is connected between resistor 351 and capacitor 352. A Zener diode 353 is connected between one side of resistor 344 and the negative terminal of the power sup- The stepping relay as shown in FIG. 7 of the drawings operates in the following manner. The silicon controlled rectifier 343 in this application is a relay control device. The silicon controlled rectifier is normally non-conducting but when its gate circuit is pulsed by means of appropriate positive timing pulses from pulse transformer 347 via the diode 345, the silicon controlled -rectifier goes into conduction and allows current to iiow through the stepping relay coil 335. VAs this coil acts to advance the relay armature 334 to the next contact positions, it also momentarily opens the normally closed interruptingy contacts 336. This reduces the anode to cathode current fiow through the silicon controlled rectifier 343 to zero so that this rectifier reverts to its original non-conducting state and thus terminates the cycle of events until the receipt lof the next positive timing pulse at some later time.

Positive timing pulses in the pulse transformer 347 are controlled through the action of the unijunction pulse transistor 350. When power is applied to the circuits of the device the capacitor 352 starts to charge up through potentiometer 349 and resistor 351. As the capacitor 352 charges up it reaches a proper firing potential so that the unijunction t-ransistor 350 goes into conduction and the capacitor 352 is discharged through this transistor and through the primary winding of the pulse transformer 347. This causes a positive pulse of the proper amplitude and time duration to be generated in the secondary winding of the pulse transformer 347. This pulse is then applied to the gate of the silicon controlled rectifier 343 as previously mentioned. Upon the completion of the discharge of the capacitor 352 .through the unijunction transistor 350, this unijunction transistor becomes non-conducting and the timing cycle starts over again. The net result of this sequence of event-s is the periodic production of timing pulses from the pulse transformer 347 which serves to advance the stepping relay armature to the next contact position.

While the timing device has been described in conjunction ywith its use on a railroad locomotive as a safety device, it should be apparent to those skilled in the art that this device can also be readily adapted for industrial uses. There are many situations in the various fields of industry where a human operator controls or supervises the operation of numerous machines or processes, and the success of these operations depends ultimately on the fact that such operator is alert and is following the operations carefully. In order to provide means whereby these operations can be controlled in the event that the human operator is not alert or is incapacitated, the timing device described herein can be used as a safety device in conjunction with vsuch operations in a very effective manner. Moreover, this timing device is arranged and constructed in such a manner that it cannot be easily tampered with or rende-red ineffect-iveto accomplish its function as a safety device.

n Two embodiments of the timing device have been shown and either embodiment is designed to function effectively in any field where there is a need for such a safety device. The embodment of the device shown in FIGS. 1, 2 and 3 of the drawings utilizes solid state components. This particular construction has many advantages such as compactness, durability, low electrical current consumption, and low maintenance costs =due in part to the fact that there are few moving parts in the device. However, such a device also involves a relatively large initial investment and therefore the second embodiment of the device which uses a stepping relay and is shown in FIG. 7 of the drawings has been disclosed as an example of a relatively less expensive device.

While, as indicated in the preceding paragraph, the choice of the particular embodiment of the timing device will necessarily depend .on economic considerations and other factors, it should be apparent that either embodi-ment of the timing device provides a reliable safety aid which can be used to advantage in many situations in the fields of transportation and industry.

The invention is not restricted to the details of the illustrated and described embodiments but is susceptible 28 to modifications and adaptations which will occur to those skilled in the art.

We claim:

l. In a timing device, visual display means including two separate series ofk electrical lamps, first and second -circuit means adapted to sequentially energize and de-energize each lamp in the first and second series respectively, said first and said second circuit means being so synchronized that the lamps in one series are thereby sequentially illuminated ata rate dierent from that of the other series, a third circuit means associated with said first and second circuit means and effective to energize signal means when the complete set of lamps in one series has been illuminated a predetermined number of times more than the complete set of lamps in the other series, fourth circuit means effective a predetermined time after said signal means are energized to energize a second signal means, manually operated means associated with the circuits of the timing device to reinitiate the simultaneous commencement of the sequential energization .of the lamps in each of the two series and de-energize said signal means at any time prior to the energization of the said second signal means.

2. A timing device as set forth in claim 1 wherein additional circuit means are connected between said first circuit means and said second circuit means, said additional circuit means being effective to prevent more than one cycle of lamp illuminations in one series unless there has been a predetermined number of lamp illuminations in the other series.

3. A timing device as recited in claim ll wherein means are associated with said first circuit means and said second circuit means to adjust the relative rates at which said lamps are energized and de-energized in said first and second series of lamps.

4. A timing device as defined in claim 1 wherein there is a second manually operated means Veffective when operated to reinitiate the simultaneous commencement of the sequential energization of the lamps in each of the two series and to de-energize said additional signal means.

5. A timing device as recited in claim l wherein additional circuit means are associated with each lamp to permit the device to continue to operate in the event of a failure of any lamp in either series.

6. The timing device as set forth in claim 1 wherein there is another means associated with said fourth circuit means to cie-energize said signal means when said second signal means is energized,

7. A timing device for use on a railroad locomotive including a visual display panel, said panel having a plurality of series of electrical lamps, circuit means adapted to sequentially illuminate the lamps of each series at different rates, additional circuit means effective to energize first signal means at a time when both lamp series simultaneously complete their respective cycles wherein each of the lamps in the series has been illuminated and extinguished, a circuit means associated with said additional circuit means and effective to energize second signal means at a predetermined time after the operation of said first signal means, means operable by the locomotive operator to reinitiate the sequential lamp illumination cycle in each series so as to prevent the operation of said first signal means or said second signal means.

8. The timing device as recited in claim 7 wherein additional means are provided whereby the rates at which the lamps are illuminated can be adjusted.

9. The timing device as in claim 8 wherein said additional means includes means responsive to the speed of the locomotive.

if). A timing device as in claim 7 wherein other means operable by the locomotive engineer are provided to deenergize the second signal means and reinitiate the simultaneous commencement of the sequential energization of the lamps in the two series.

11. A timing device as set forth in claim 7 wherein said second signal means includes an audible signal together with circuits designed to operate valve means in the air brake system of the locomotive to apply the brakes when said second signal means is energized.

12. A timing device as recited in claim 11 including electrical switch means in the air brake system, said electrical switch means being associated with said first and second circuit means whereby the sequential illumination of the lamps in the plurality of series of lamps is halted when brake application is manually initiated from the locomotive cab, said electrical switch means being effective to permit a continued sequential illumination of said lamps in each series when the locomotive brakes are subsequently released. Y

13. An electronically controlled timing device ineluding a source of electrical energy operatively connected t0 a rst series of lamps and a second series of lamps, solid state electronic lamp pulse circuit means and solid state electronic ring counter circuit means associated with said lirst series of lamps, solid state electronic lamp pulse circuit means and solid state electronic ring counter circuit means associated with said second series of lamps to sequentially energize and de-energize each lamp in each of said series in a predetermined time sequence, in com- 36 bination with circuit means to energize a warning signal after a predetermined number of cycles of lamp energization in each of said series, and manually operated means associated with the circuits of the timing device to reinitiate the simultaneous commencement of the sequential energization of the lamps in each of the series.

14. A timing device as set forth in claim 13 wherein additional circuit means are associated with the circuit means for energizing a Warning signal to energize a second signal a predetermined time after the energization of said warning signal if the said manually operated means has not been actuated to reinitiate the sequential energization of the lamps.

15. The timing device recited 'by claim 14 installed on a locomotive wherein said additional circuit means effect a brake application after said predetermined period of time in the absence of an actuation of said manually operated means to reinitiate the simultaneous commencement of the sequential energization of the respective lamps in each of the series.

16. The combination deined by claim 15 which includes means responsive to the speed of the locomotive for controlling the rate at which the lamps are energized in each of said series of lamps.

No references cited.

EUGENE G. BOTZ, Primary Examiner. 

1. IN A TIMING DEVICE, VISUAL DISPLAY MEANS INCLUDING TWO SEPARATE SERIES OF ELECTRICAL LAMPS, FIRST AND SECOND CIRCUIT MEANS ADAPTED TO SEQUENTIALLY ENERGIZE AND DE-ENERGIZE EACH LAMP IN THE FIRST AND SECOND SERIES RESPECTIVELY, SAID FIRST AND SAID SECOND CIRCUIT MEANS BEING SO SYNCHRONIZED THAT THE LAMPS IN ONE SERIES ARE THEREBY SEQUENTIALLY ILLUMINATED AT A RATE DIFFERENT FROM THAT OF THE OTHER SERIES, A THIRD CIRCUIT MEANS ASSOCIATED WITH SAID FIRST AND SECOND CIRCUIT MEANS AND EFFECTIVE TO ENERGIZE SIGNAL MEANS WHEN THE COMPLETE SET OF LAMPS IN ONE SERIES HAS BEEN ILLUMINATED A PREDETERMINED NUMBER OF TIMES MORE THAN THE COMPLETE SET OF LAMPS IN THE OTHER SERIES, FOURTH CIRCUIT MEANS EFFECTIVE A PREDETERMINED TIME AFTER SAID SIGNAL MEANS ARE ENERGIZED TO ENERGIZE A SECOND SIGNAL MEANS, MANUALLY OPERATED MEANS ASSOCIATED WITH THE CIRCUITS OF THE TIMING DEVICE TO REINITIATE THE SIMULTANEOUS COMMENCEMENT OF THE SEQUENTIAL ENERGIZATION OF THE LAMPS IN EACH OF THE TWO SERIES AND DE-ENERGIZE SAID SIGNAL MEANS AT ANY TIME PRIOR TO THE ENERGIZATION OF THE SAID SECOND SIGNAL MEANS. 